Marco Rubio (AP Photo/Jae C. Hong, File)

Though most of the political media’s attention may be on Hillary Clinton, another candidate is entering the 2016 presidential race today. This morning Marco Rubio semi-officially announced on a conference call to donors that he will in fact be running (“Rubio says he has always felt the United States is about tomorrow,” reported the AP, showing what bold and controversial stances he may be taking), with the dramatic rally scheduled for this evening in Miami.

For a guy who just two years ago appeared on the cover of Time magazine over the headline “The Republican Savior,” Rubio has been getting relatively little attention lately. HuffPost Pollster’s aggregation of polls puts him tied for seventh in the primaries, at a measly 5.4 percent support among Republicans. But at this stage of the race anyway, Rubio looks like the most formidable general election candidate the GOP has, even if Republican voters don’t seem to know it yet.

The question is whether the obstacles Rubio faces in the primaries are too large to overcome. The answer may shed light on how factionalized the party really is.

The characteristics of the Republican field could make Rubio everyone’s second choice. If you’re a tea partier looking for the most conservative candidate, you might gravitate to Ted Cruz or Scott Walker. Though the actual policy differences between them and Rubio are somewhere between tiny and non-existent, Rubio’s rhetoric isn’t nearly as belligerent, so many base voters will assume he’s isn’t quite so far to the right. If you’re a Christian conservative looking for the most religious candidate, there are many others (Cruz, Mike Huckabee, Bobby Jindal) making more of a direct pitch for your votes. If you’re more of a libertarian, you’ll gravitate toward Rand Paul. If you’re a moderate seeking a safe, traditional candidate, Jeb Bush is your man. Rubio could end up being the candidate everyone feels warmly about but relatively few end up voting for.

We often describe the GOP primary process as a battle between these factions, with each one settling on their favored candidate, then begrudgingly accepting the results when another faction’s champion prevails. It’s probably a bit overstated — there are going to be at least some people of different types voting for most of the contenders — but the last few years have seen especially bitter conflicts within the Republican Party. Greg and I have both argued before that the most likely nominee is the one who can bridge those gaps, particularly the biggest one, between the tea party base and the more pragmatic establishment. Even if no candidate can be all things to all factions, you can’t win the nomination without a healthy chunk of all the major Republican groups.

There are some reasons to think Rubio could do that, but much of what makes him compelling is better suited to the general election than the primaries. He’s a smart guy who can be compelling on the stump and charming in small groups. The fact that the Tea Party cast him out when he wrote a comprehensive immigration reform bill could be a benefit in the general, as it would enable him to portray himself as a moderate (even if he eventually reversed himself on immigration and now advocates the same “border security first” position as most every other Republican).

Meanwhile, Rubio has been particularly vocal in suggesting he has an economic plan centered on the middle class. The reality, as Brian Beutler argues today, is that it’s just as much a giveaway to the wealthy as every other Republican plan. But Rubio wouldn’t necessarily be unable to convince people otherwise. If he were the nominee, he would improve the party’s showing among the vital and growing Latino electorate; there’s no telling by how much, but he would almost certainly do better than the 31 percent John McCain got or the 27 percent Mitt Romney got.

But in a party at war with itself, Rubio has no natural constituency to build from. In this field, he’s not the most anything: not the most partisan, not the most anti-government, not the most socially conservative, not the most beloved by Republican elites. All of which means he could be setting himself up to be the perfect vice-presidential candidate. At only 43 years old, he could do a lot worse.